Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02870189 2014-11-12
IMPROVED APPARATUS AND METHODE FOR MEASURING AND
MONITORING THE WATER HEIGHT LEVEL AND CORRESPONDING VOLUME
OF OVERFLOW WATER IN SEWER OVERFLOW CHAMBER
FIELD OF THE INVENTION
This invention relates to an apparatus and method for measuring and monitoring
more
precisely the water level and associated water volume and water flow rate on a
sewer
overflow chamber.
BACKGROUND OF THE INVENTION
With the recent changes in global weather, aged municipality sewer systems are
often
stressed beyond designed capacities, causing increases in waste water
overflow. Such
waste water overflow needs to be monitored in a number of events, volume per
event,
water flow rate per event, etc. Such a monitoring system must initially
measure
accurately the height of the water level at the physical point of overflow
needed to
calculate the corresponding water overflow rate.
Current measuring equipment systems either use hydrostatic pressure sensor or
ultrasound liquid level sensor including a combination of both. Both equipment
are
prone to measurement error, especially in water overflow chamber,
characterized by high
turbulence, high volume of debris and high risk of surface foam formation.
Current calculations of the water overflow rate corresponding to a measured
overflow
water level multiply the water level measurement error into higher water
overflow rate
calculation error. In addition, the complexity of some water overflow chambers
contribute to increasing the overall calculated water overflow rate.
Most industrialized countries regulate municipalities to report every sewer
water
overflow incident. While some regulations call only to report the number of
incidents per
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CA 02870189 2014-11-12
time period (i.e. per week) independent of the total volume of overflowed
sewer water
per incident, other regulations call to report the volume of overflowed sewer
water per
incident. The latter case is known by government authorities to be prone to a
wide range
of errors, starting from water height equipment measurement error to the
corresponding
calculated water overflow rate error, making government authorities reluctant
to filling
regulations that call on municipalities to publish water overflow rate per
incident.
Current techniques to reduce the error are known to be expensive in equipment
acquisition and installation fees. One technique to reduce the water height
equipment
measurement error is to combine the hydrostatic water pressure sensor with the
ultrasound water level sensor. One technique to reduce the corresponding
calculated
water overflow rate error is to add a water flow rate equipment in the water
overflow
channel.
This invention presents an apparatus and a method that contributes to reducing
substantially both; the water height measured error as well as its
corresponding calculated
water overflow rate error with minimum equipment acquisition and installation
fees. It
is based on the installation of a camera inside the overflow chamber, aimed at
the point of
overflow, assisted by a ruler mounted beside the point of overflow, where
still pictures or
video are taken at the time of overflow triggered by the water level
measurement
equipment. The picture showing; the water level ruler reading, the water level
surface
condition and the water level slant angle at and nearby the area of overflow,
contributes
collectively when integrated with current water level measuring equipment
(either
hydrostatic pressure or ultrasound level equipment, including simple water
presence
sensor) to reduce the water level measurement error as well as its
corresponding
calculated water overflow rate error.
PRIOR ART
There is a plurality of pipe sewer inspection camera, mainly used to find and
locate pipe
flow anomaly and root cause of water leak. The USA owned, Canadian patent
application CA 2309018 filled in 2000, entitled, Improved Apparatus for
Inspecting
Lateral Sewer Pipes, by Michael R. McGrew, describe such typical camera based
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CA 02870189 2014-11-12
application with emphasis on its motion characteristic within the sewer piping
system.
The more recent Canadian owned and patent application CA 2798446 filled in
2011,
entitled, Method of Inspecting and Preparing a Pipeline, based on the
assistance of a
camera also restrict its application to sewer pipe.
Advanced patent search could not produce any prior art filled patent nor
patent
application based on this invention.
Therefore, the main advantages of this invention are: improvement of sewer
water
overflow height measurement accuracy at the point of overflow, improvement of
the
corresponding calculated sewer overflow rate accuracy needed to calculate the
overall
volume of sewer water overflow per incident, at a minimum equipment
acquisition and
installation cost.
SUMMARY OF THE INVENTION
The present invention presents an apparatus and a method of improving the
accuracy of
measuring the sewer water height level of overflow and corresponding
calculated
overflow rate and corresponding total volume of overflow sewer water per
overflow
incident without substantially increasing the number and cost of additional
measuring
equipment such as flow meter equipment which required high maintenance level.
Thus, in accordance with one aspect of the invention, a wireless digital
camera is
positioned inside the overflow chamber such that the field of view of the
camera lens is
aimed at the point of overflow, where a scaled ruler is mounted to be also in
the field of
view capturing in the picture the water sewer height level.
As an added benefit, the picture is used to define the sewer water surface
conditions when
the presence of debris, foams, waves and turbulence is known to be the cause
of error in
measuring the sewer water height level with electronic equipment such as
hydrostatic
pressure or ultrasound sensor, whereas ultrasound sensor is known to be more
problematic under difficult sewer water surface conditions.
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CA 02870189 2014-11-12
When the sewer height level measurement equipment is already equipped with
communication means to relay the measured data to a backend or Internet portal
system,
the wireless camera uses the existing equipment communication means to relay
its
pictures to the same backend or Internet portal system.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of example only,
with
reference to the accompanying drawings, in which:
Figure 1 is a block diagram and data flow diagram of the overall system
Figure 2 is a picture of a Go-Pro classic water submergible digital wireless
camera.
Figure 3 is a picture a classic large scale survey type ruler.
Figure 4 is a picture of a classic hydrostatic pressure water level
measurement equipment
equipped with a wireless transmitter mounted at the other end in order to
maintain
wireless communication with the camera under a sewer overflow condition.
Figure 5 is a picture taken by the camera mounted on the wall of a sewer
overflow
chamber, showing also the ruler.
Figure 6 is a picture taken by the camera mounted under the man hole cover,
showing the
PVC pipe used to guide the insertion of the hydrostatic pressure water level
measurement
equipment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In figure 1, an overall system block diagram and data flow diagram such as the
picture
taken from the wireless camera (bottom left corner of the block diagram) is
sent to the
wireless hydrostatic pressure sensor, which sent to the wireless gateway,
which sent to
the wireless reader, which send via different wireless root the picture to the
data center
where the sewer water level data of the picture is process.
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CA 02870189 2014-11-12
In figure 2, a classic battery operated waterproof wireless digital camera
such as the
popular Go-Pro camera is mounted on the sewer chamber wall in opposite
distance to the
area of overflow.
In figure 3, a classic scaled ruler such as the one used by surveyor is
mounted on the
sewer chamber wall adjacent to the area of overflow. To assure reliable
readings at all
times the lower part of the ruler is positioned to be below the start point of
the overflow
level, ideally submerge in the normal (non-overflow) running sewer water.
In figure 4, a non-classic hydrostatic pressure sensor includes a wireless
radio receiver a
transmitter at the upper end of the sensor, allowing for maintaining the
wireless radio
antenna above the water level during overflow condition. Being located above
the
overflow water level, the hydrostatic pressure sensor maintains wireless
communication
with the wireless camera also positioned above the overflow water level. Since
the
ultrasound sensor is known to be more problematic under difficult sewer water
surface
condition, the preferred sewer height water level sensor is a hydrostatic
pressure sensor.
When the hydrostatic pressure sensor detects the start point of an overflow
condition, it
wirelessly wakes-up the wireless camera, calling for taking a picture of the
overflow area
tagged with date and time. Likewise, when the hydrostatic pressure sensor
detects nearby
the reach of the maximum point overflow level it calls for a second picture.
Finally,
when the hydrostatic pressure sensor detects the end point of the overflow it
calls for a
third picture. The three pictures collected are then transmitted to the
hydrostatic pressure
sensor which relay the pictures to the backend or Internet portal system via
its existing
wireless communication means, allowing for checking the calibration at low and
high
readings and to be sure that the hydrostatic pressure sensor recovers
accurately on the
way down.
In figure 5, a picture taken by the wireless camera showing a horizontal view
of a sewer
chamber with the hydrostatic pressure sensor located to the left side of the
picture at the
bottom end of the white PVC pipe and with the ruler located to the right side
of the
picture beside the point of overflow. The picture was taken in absence of a
sewer water
overflow situation.
CA 02870189 2014-11-12
In figure 6, a picture taken by the wireless camera showing a vertical view of
man-hole
accessing a sewer overflow chamber. The white PVC pipe is used to guide the
insertion
of the hydrostatic pressure sensor within the pipe, where the pipe
strategically ends at the
start point of the sewer water overflow. The ruler is not shown in the
picture.
Once the hydrostatic pressure water sewer height level data combined to the
pictures are
saved at the backend or Internet portal system, image processing is applied to
extract the
water sewer height of overflow at the time of the picture taken via the usage
of the scaled
ruler showing the water level line intersection on the ruler. At the current
stage of the
invention, human processing is used to extract such water level height. Such
water level
height extracted from the picture is used to back-up the sewer water height
level
produced by the hydrostatic pressure sensor. Also at the current stage of the
invention,
human processing is used to analyze the sewer water surface condition,
including the
surface slant angle at the point of entry into the overflow escape area. Such
surface
condition will contribute in the calculation of the corresponding overflow
rate and finally
the total volume of overflow sewer water.
In the future, video analytic signal processing will be used to automatically
extract the
sewer water height level; whereas such water height level data will be
integrated with the
hydrostatic pressure water sewer height level data to produce an overall
confidence level
of integrated overflow sewer water height level.
Likewise, in the future, video analytic signal processing will be used to
extract the sewer
water surface condition and direction of water flow at the overflow escape
area.
Other preferred embodiments:
A further application of the invention also applies to replace mandatory human
physical
inspection of overflow chamber on a regular basis. The wireless camera takes
pictures at
present fixed time interval, even in absence of overflow condition.
A further application of the invention uses an ultrasound sewer water height
level
measurement equipment in replacement or in combination with a hydrostatic
pressure
sewer water height level measurement equipment.
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